Abstract: A transgenic animal is provided. In certain embodiments, the transgenic animal comprises a genome comprising: an immunoglobulin light chain locus comprising: a) a functional immunoglobulin light chain gene comprising a transcribed variable region encoding: i. light chain CDR1, CDR2 and CDR3 regions that are composed of 2 to 5 different amino acids; and ii. a light chain framework; and, operably linked to the functional immunoglobulin light chain gene: b) a plurality of pseudogene light chain variable regions each encoding: i. light chain CDR1, CDR2 and CDR3 regions that are composed of the same 2 to 5 different amino acids as the CDRs of the functional gene; and ii. a light chain framework that is identical in amino acid sequence to the light chain framework of the transcribed variable region.

Abstract: A gel microdrop composition is provided. In certain embodiments, the gel microdrop composition contains a polymer matrix, an effector particle that releases an effector molecule into the polymer matrix, a first reporter particle that emits a first optically detectable signal and a second reporter particle that emits a second optically detectable signal that is distinguishable from the first optically detectable signal, where the effector particle and said first and second reporter particles are encapsulated by the polymer matrix. Methods of screening that employ the gel microdrop composition and methods of making the gel microdrop composition are also disclosed.

Abstract: A gel microdrop composition is provided. In certain embodiments, the gel microdrop composition contains a polymer matrix, an effector particle that releases an effector molecule into the polymer matrix, a first reporter particle that emits a first optically detectable signal and a second reporter particle that emits a second optically detectable signal that is distinguishable from the first optically detectable signal, where the effector particle and said first and second reporter particles are encapsulated by the polymer matrix. Methods of screening that employ the gel microdrop composition and methods of making the gel microdrop composition are also disclosed.